Doublet or Dipole? - Part 1

I want an alternative to my 1/4 ground mounted vertical antenna for the 80m band. After much research and garden measurements I have gone for a 135ft/41.15m doublet. In part 1 I install and test the doublet. See how I get on...
Part 2 of this series can be found at: • Doublet or Dipole? - P...
Part 3 of this series can be found at: • Fan Dipole Experiment ...
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Thanks.
Ian.

[@gbamck]

Cheers for the video, Ian. Looking forward to part 2. It's great to see an amateur with enough room to get a decent wire up 👍- so many of us restricted more and more.

[@ianxfs]

Thanks Mick! I was a bit wary about going round the front as it’s all open plan. I used 100lb braid fishing line to try and be as in invisible as possible. Nobody’s commented so far....

[@Steve_Wardley_G6JEF]

I'll second that. I've got a six foot by thirty foot concrete wheelie bin yard surrounded on three sides. Ugh !

[@gbamck]

@@Steve_Wardley_G6JEF same mate. Fortunately I've got a skylight so I've got a 20m EFHW fed at the bottom of a 10m pole at the end of the garden with a 49:1 transformer - so 10m up vertical then 10m flat across to the skylight inverted L. The noise is off the scale though living in Coronation Street style proximity. 😐

[@ronjoseph7973]

The doublet is perhaps the most robust and forgiving wire antenna around. With a 1:1 choke balun, there is no worry of common mode current in the shack as opposed to an end fed antenna whether it be half wave or random wire. I use a ZS6BKW which is resonant on 40, 20, 17, 12, and 10 meters, depending on configuration. I use a broadband autotuner which makes multiband operations a breeze as opposed to having a separate dipole for each band.

[@ianxfs]

Thanks for the information Ron 😀

[@markg6jvy135]

Look forward to pt2 👍👏👏

[@ianxfs]

Thanks Mark!

[@kevinkc3onohelijeepworld953]

Doublet Collins multi band but use open spaced feed line 4” electric fence ribbed isolators and uv resistant DuPont 66 wire ties 13” long. And multi band the antenna from 80-6m 😉 looks great 👍

[@ianxfs]

Sounds good Kevin!

[@garyhinson3876]

i have a doublet, not as long as this one, but cut to one of the recommended lengths, the ladder line drops down into a home brew remote balanced tuner, it would tune on all the HF bands except 40M, eventually, the solution was to add about 500mm to each leg M0IUQ

[@ianxfs]

Thanks Gary. Sounds like you’re sorted with yours 👍🏻

[@stewartrv]

Before you take it all down and get the dipole up, I'd try getting the tuner directly on ladder line rather than behind the choke just to see how it looks then, I know you have a 991a so I guess you can use it in the garden direct to the tuner (weather permitting) for test purposes. I too am planning to put one up in my garden as a test, already have tuners so need to make up the doublet and ladder line. I have had a fan-dipole in the past and it was very very good, just three elements on it for 80, 40 and 20 and it would also tune many others. You might have issues because of the roof though. If you do, then it's probably why the doublet has issues too.

[@ianxfs]

Thanks Stewart! I tried a different type of choke yesterday with no real change. I’ll see if I can connect to unbalanced input of tuner before it comes down. Less windy today 👍🏻

[@stewartrv]

Good luck with it!

[@ianxfs]

@@stewartrv tinkering now....

[@timg5tm941]

V good Ian

[@ianxfs]

Thanks Tim! When these gales drop, I’ll get the dipole up 👍🏻

[@primozbricelj7244]

I have a 70 m (35m per leg) doublet fed with 300 ohm ladder line connected directly to a balanced tuner mfj 993b. Tunes everything from 160 and up. I think the main point is the lenght of a dublet should not be resonant at any ham band, so 41 meters i think is not a good size. Also balanced tuners have 4:1 balun built in or atleast my has it. So in case the tuner doesn't have a balanced output, you should put a 4:1 and the shortest posible lenght of coax to tuner. The losses on balanced line with high swr are negligible. I hope i am not totaly wrong here but it works for me. Good luck 73.

[@ianxfs]

Thanks and congratulations on your long doublet! The tuner was unbalanced and the latest thinking is use a 1:1 balun to present a high impedance to the tuner. A 4:1 can sometimes present a very low value (

[@adyg6ad73]

That tuner looks like my Capco SPC300a. Good luck with the doublet. I hope to hear you on 80m soon.

[@ianxfs]

Yes Ady. Well spotted. Capco innards 😁

[@robduncan599]

I have a fan dipole 80/40 going east west one on top of the other 40 more inverted v . Works great . Yet i am a big fan of the doublet. That atu will definitely tune a doublet it just needs a afternoon getting it just right ? If you go with the doublet the main thing is symmetry! 135 ,120 or 100 feet will make little difference? Symmetry might be tricky with roof ? I try to avoid 1/2 wave lengths 140 was a good lengh for me . Good luck .

[@ianxfs]

Thanks Rob!

[@K1ZEK]

Nice video..

[@ianxfs]

Thanks!

[@meggalavk3ktt]

i have struggled with these a 4 to 1 balun might help i love my 80m dipole i did have a 40m delta loop. noting beat it till my steppir i would think 25m a side might be a better length any way a good video as always

[@ianxfs]

Thanks! Yes when I researched a lot were using 1:1 baluns to give the tuner a high figure to bring down, rather than a low figure it can’t tune higher. Anyway, the dipole in part 2 is working really well 😀